The invention relates to a multiple light emission control system utilizing electronic flashes, and more particularly, to such a system in which the emission of light from a plurality of electronic flashes is controlled to different values, in a flash photography of the type in which the emission of flashlight from the electronic flashes is automatically interrupted in response to an emission interrupt signal produced whenever a proper exposure has been determined as a result of the interception by a photometric element disposed within a camera of light passing through a taking lens of the camera after being reflected from an object being photographed which is illuminated by the flashlight from the electronic flashes.
FIG. 1 illustrates an exemplary arrangement to provide a multiple light photography utilizing a plurality of electronic flashes. As shown, a pair of electronic flashes A and B are connected to a single camera C. Such an arrangement is frequently used to take a picture while supplying suitable amounts of light to an object D being photographed from both lateral sides. In this instance, the relative amount of light emitted from the both electronic flashes A and B can be adjusted so that the object can be illuminated in a stereographical manner, thus permitting a photographer to produce an image construction as intended.
In the prior art practice, a number of different techniques can be employed to change the relative amount of emission from the electronic flashes. By way of example, different guide numbers may be used on the individual electronic flashes A and B, which are then manually operated for emission of the flashlight. Alternatively, different ND (neutral density) filters may be mounted on the respective electronic flashes A and B in order to control the emission of light therefrom. As a further alternative, the point in time when the emission of flashlight from the respective electronic flashes A and B is initiated is displaced from each other, thereby controlling the emission of flashlight.
Recently, an arrangement which is commonly referred to as TTL "auto-strobo" is in practical use, and can be used to effect a multiple light photography. In this instance, a plurality of "strobos" are used, which are electronic flashes having the capability to terminate the emission of light in response to a signal which is internally produced within an individual electronic flash or supplied externally from an associated camera. When this is applied to the arrangement shown in FIG. 1, since the electronic flashes A and B, representing such "strobos", are controlled by an emission interrupt signal from the camera C, it follows that the emission of light from the electronic flashes will be equal to each other if the electronic flashes A and B are disposed at an equal distance from the object D. The change the emission of light supplied from the respective electronic flashes A and B upon the object D, they must be located at different distances from the latter. However, a practical manner of establishing such distances depends solely on the perception of the situation by the photographer. Also there are occurrences in which satisfactory distances cannot be assured, depending on the location where the picture is taken. Thus it follows a control of the relative emission of light from a plurality of electronic flashes must resort to a manual photographing technique.